Issues creating object literal using anonymous types in c#

Question

I'm trying to build the c# approximation of a JavaScript object literal to be passed to a view model in asp.net MVC:

var obj = new dynamic[]{
    new { name: "Id", index: "Id", width: 40, align: "left" },
    new { name: "Votes", index: "Votes", width: 40, align: "left" },
    new { name: "Title", index: "Title", width: 200, align: "left"}
};

The compiler is throwing:

"An anonymous type cannot have multiple properties with the same name"

Stab in the dark I'm guessing it can't distinguish between the which property goes with which anonymous object, I've seen a similar error using LINQ.

Is there a better way to accomplish what I'm trying to do?

EDIT: This is in VisualStudio 2010 and .net Framework 4. Bala R's Answer seems to address the problem for previous versions though.

Did you mean to use `:` syntax between property values instead of `symbol=value`? — Tejs, Apr 26 '11 at 19:56
@priyank yes, but out of context, should I post the rest? @tejs yes I'm trying to mirror JavaScript object literal syntax — Graham Conzett, Apr 26 '11 at 20:21
@tejs I changed it to the syntax Bala R posted below though. — Graham Conzett, Apr 26 '11 at 20:51
Don't know if you are trying to do JSON serialization, if so, there are some built-in features that could help: http://encosia.com/2011/04/13/asp-net-web-services-mistake-manual-json-serialization/ — Dan Sorensen, Apr 27 '11 at 06:11
@Dan great read, thanks for that. Unfortunately I need a JavaScript object literal and not a JSON object, and there doesn't seem to be a good clean method for serializing the former. I think I will end up using javascript serialization in the app and parse the JSON to an object on the client side, a little more work for the client but cleaner than passing the object literal as a string. — Graham Conzett, Apr 27 '11 at 15:03
@Graham: JSON is just the serialized representation of a JavaScript object literal. JSON is exactly how you should transmit JavaScript objects if you're sending them to a browser or somewhere else with good JSON parsing/deserialization utilities. — Dave Ward, Apr 27 '11 at 17:21
@Dave: Thanks, for stupid reasons it was initially decided not to do client side parsing of JSON which was the reason for passing the object literal as a string. Luckily, we've made the switch to parsing it normally (which should have happened from the beginning)! — Graham Conzett, Apr 27 '11 at 17:50

Bala R · Accepted Answer · 2011-04-26T19:29:49.490

6

Can you try this?

var obj = new[]{
    new { name= "Id", index= "Id", width= 40, align= "left" },
    new { name= "Votes", index= "Votes", width= 40, align= "left" },
    new { name= "Title", index= "Title", width= 200, align= "left"}
};

and you should be able to access the anonymous class array like this

if (obj[0].align == "left")
{
   ...
}

edited Apr 26 '11 at 19:29

answered Apr 26 '11 at 19:16

Bala R

107,317
23
199
210

Still seems to be throwing the same error, good thought though. – Graham Conzett Apr 26 '11 at 19:18
I don't have any compilation errors. Note: I removed `dynamic` because i don't think it's required in this case + I don't have vs2010 and .net 4 :) – Bala R Apr 26 '11 at 19:19
Hmm, yes running VS2010 and .net 4 here, I'll add that to the information in the original question. – Graham Conzett Apr 26 '11 at 19:27
I can access the class array and it shows up with intellisense, but it still throws the error at compile time. – Graham Conzett Apr 26 '11 at 19:33
When I remove the `dynamic` declaration i get: `Invalid anonymous type member declarator. Anonymous type members must be declared with a member assignment, simple name or member access.` – Graham Conzett Apr 26 '11 at 19:40
1

I tested @Bala R's code on .NET 4 vs2010. It works, its something you're doing. Copy and paste his code and see if it compiles. – contactmatt Apr 26 '11 at 19:45
see this http://ideone.com/dtiVP it compiles and works. Your problem could be somewhere else, maybe? – Bala R Apr 26 '11 at 19:47
1

@contactmatt Thanks for confirming, will investigate further. – Graham Conzett Apr 26 '11 at 19:49
this version doesn't use a dynamic object, it generates an anonymous object – BlackTigerX Apr 26 '11 at 19:50
@Bala R - that's a sweet tool – BlackTigerX Apr 26 '11 at 19:50
@Bala R After changing it again and rebuilding it now, works, not sure what was going on before. Marking as answer. – Graham Conzett Apr 26 '11 at 20:51

Issues creating object literal using anonymous types in c#

1 Answers1

Linked